1. Field of the Invention
This invention relates to a sewing machine with functions for performing pattern stitching, button hole stitching, automatic edge stitching and so forth, and more particularly, to a sewing machine provided with an abnormal condition warning means for giving a warning of an abnormal condition by changing a color of light.
2. Description of Related Art
Conventionally, in sewing machines of the type mentioned, when an operator makes an error in operation, when the remaining amount of bobbin thread decreases to a certain level or when a needle thread is broken, a control device indicates such information on an indicator to give a warning of the abnormal condition to the operator. Such an indicator may include a plurality of LED's, one of which is selectively lit corresponding to a message of an abnormal condition printed on a panel, or may include a liquid crystal display unit for displaying a message of an abnormal condition thereon. Such an indicator may include, as alternative means for giving a warning of an abnormal condition to an operator, a sound emitting device from which a message of an abnormal condition is generated by sound.
A sewing machine is disclosed in U.S. Pat. No. 4,763,589 wherein an LED provided at the sewing head is lit, when a bobbin thread is consumed to a certain low bobbin thread condition, thereby providing a warning to an operator.
Another sewing machine is disclosed in U.S. Pat. No. 4,481,507 wherein, when a needle thread is broken, a thread breakage detector detects such breakage and outputs a signal to a sound emitting device. More particularly, a thread breakage detector disposed along a supply route of the needle thread detects tension of the thread by means of a microswitch or an optical sensor. Such a signal is then transmitted to a microprocessor. The microprocessor outputs the signal to a sound emitting device, and consequently, the sound emitting device emits sounds representative of an abnormal location. For example, a warning message of an abnormal condition of "a thread is broken" can be given to an operator.
However, with sewing machines of such construction wherein an LED is energized to emit light or a message of an abnormal condition is displayed on a liquid crystal display unit, since the indicator is small in size, an operator may possibly not be made aware of such a message of an abnormal condition and may, therefore, repeat the same erroneous operation. On the other hand, with sewing machines of the construction wherein a message of an abnormal condition is developed by sound by a sounding emitting device, an operator sometimes misses the message of an abnormal condition thus developed by sound. Thus, in this instance as well, there is the possibility that the same erroneous operation may be repeated.